Page "Light-emitting diode" Paragraph 15

The first commercial LEDs were commonly used as replacements for incandescent and neon indicator lamps, and in seven-segment displays, first in expensive equipment such as laboratory and electronics test equipment, then later in such appliances as TVs, radios, telephones, calculators, and even watches ( see list of signal uses ).

These red LEDs were bright enough only for use as indicators, as the light output was not enough to illuminate an area.

Readouts in calculators were so small that plastic lenses were built over each digit to make them legible.

Later, other colors grew widely available and also appeared in appliances and equipment.

As LED materials technology grew more advanced, light output rose, while maintaining efficiency and reliability at acceptable levels.

The invention and development of the high-power white-light LED led to use for illumination, which is fast replacing incandescent and fluorescent lighting